Imidazolone color formers



and No.

Patented June 3, 1947 UNITED STATES PATENT OFFICE IMIDAZOLONE COLOR FORMERS Benjamin Ramage Harriman,

assignor to General tion, New York, N. Y.

ware

Binghamton, N. Y., i: Film Corporaa corporation of Dela- 11 Claims. (01. 95-6)- The present invention relates to color photography and, more particularly, to color forming or coupling components suitable for use in the process of color forming development, in which color is produced in a photographic emulsion layer by the action of an oxidation product of the photographic developer on a dyestuif component present in said layer during development.

The present invention is an improvement on the process of color forming development first described in United States Patents No. 1,055,155

which a color forming development component which is incorporated either in the photographic emulsion layer or in the development bath, and which when the emulsion layer is developed by means of a developer containing free amino groups, for instance, aromatic diamines, especially the monoor unsymmetrically oli-substituted ones, like p-dimethylaminoaniline, or methoxy-p-dimethylaminoaniline, couples with the oxidation product of the photographic developer to form a dyestuif at the points where a silver image is produced. In accordance with more recent developments of this process, it is preferable to employ, as the color forming or coupling component, a compound which is nondifiusing in the photographic emulsion, rather than one which is soluble in the photographic developing solution. This is particularly true if several difierently sensitized emulsion layers are cast on a single support, as is the case in the so-called integral tripack photographic color films, since in such case, any wandering or diffusing of a color coupling component from the emulsion layer in which it is incorporated to another will cause inaccurate color rendition.

In such color forming development process, it has been customary to employ various pyrazolones for the production of red or magenta pictures. The coupling takes place at pointswhere a silver image is formed between the oxidation product of the color forming developer and the active methylene group of the pyrazolone ring. It is recognized, however, that many of the pyrazolones that may be employed as magenta color coupling components have a relatively high blue adsorption and therefore are not entirely satisfactory as color forming components.

1,102,028 to Fischer, in accordance with It is an object of the present invention to provide a new type of color forming components, closely related to the pyrazolones, in which the heterocyclic ring is slightly modified without destroying the active methylene group. Other and further objects will become apparent as the following description progresses.

I have discovered that the imidazolones are valuable color forming components and that many imidazolones may be obtained which produce particularly valuable magenta colors on coupling with the oxidation product of a color forming developer and that such coupling, between the active methylene group of the imidazolone ring and the oxidation product of the color former developer, is readily brought about by the usual color forming development processes.

The imidazolones which I have found are particularly valuable as color forming components may be represented by the following general formula:

in which It stands for hydrogen, alkyi, aryl, aralkyl, or acyl, which may be further substituted; for instance, by amino, acyl, acylamino, sulfo, nitro, hydroxy, amino sulfo, etc.; R stands for the residue oi a pyridina'quinoline or isoquinoline radical, which may be further substituted; and X is a negative substituent, such as halogen, carboxyllc or sulfonic acid group, or the like.

The imidazolones which I employ as color forming components may readily 'be prepared by known methods of synthesis. A convenient method by which to prepare these imidazolones is to employ 2-amino-pyridine or quinoline as the starting material and react this with an a-halogenated acyl halide, for instance, monochloro acetic acid chloride. This reaction may readily be carried out in dry ether or other anhydrous solvent at room, temperatures. A hydrochloride is formed first and this is dumped in water so that hydrochloric acid is split off and the chloro acyl amino compound precipitates. This material may then be separated by filtration, dried, disring is quaternized and the amino group cyciicized with the resulting formation of an imidazolone ring. The above series of reactions takes place in accordance with the following Equation I:

NH, N

NH-CO-CHaCl HC] NNH iii.

and is particularly valuable in case 2-aminoquinoline is employed as a starting material.

An alternative method of preparing imidazolones, suitable for use in accordance with the present invention, and which is slightly more satisfactory in case Z-amino-pyridine is employed as a starting material, but which does not function so well in case quinolines are employed, is to react the Z-amino-pyridine with the sodium salt of monochloroacetic acid,.thus quaternizing, the amino group of the pyridine ring and forming a cyclic salt. The thus-obtained cyclic salt may be dehydrated readily in accordance with conventional procedures to form thereby an imidazolone ring. This method of synthesis may be represented by the following Equation II:

Eq. II

Other methods of synthesis will also suggest themselves to those skilled in the art. 7 Thus, if desired, the imidazolone may be obtained directlyby heating together substantially equal molecular amounts of 2-amino-pyridine and an ester of monochloroacetic acid, as represented by the following Equation III:

The solubility of the imidazolones prepared as described above may be modified by the nature of the substituents thereon. Thus, a convenient method of obtaining non-diffusibility in the imidazolone is to introduce a long chain alkyl substituent on the nitrogen atom in l-position. An imidazolone containing such a substituent is readily obtained by employing, as a starting material, a. pyridine or a Z-amino-pyridine or quinoline in which the amino group contains a long chain alkyl group. Non-diflusibility is obtained when the alkyl group of the amine contains 8 or mor carbon atoms.

In a similar manner, the particular shade or color obtained may be influenced, to a large extent, by the nature of the substituents in the pyridine ring.

The following specific examples are illustrative of the present invention:

. Example 1 2-keto-4-chloro-imidazo[1,2-a] pyridine, prepared as outlined above in Equation II, was incorporated in a photographic emulsion in the usual manner by dissolving the same in an aqueous solution, for instance, by dissolving a small amount, say 8 grams, in ml. of water. The thus obtained photographic emulsion was cast on a suitable support to produce a photographic iilm, which after exposure and development with a color forming developer, p-diethylaminoaniline, gave a magenta picture. The color coupling component, however, was diffusible from the photographic emulsion.

In order to overcome this difiusibility in the photographic emulsion, a similar compound, 1- octadecyl-Z-keto-4-chloro-imidazo [1,2-a] pyridine, was prepared in the manner outlined under Equation II above, substituting Z-octadecylpyridine for the 2-aminopyridine there mentioned. 4.0 grams of this product were dissolved in 100 ml. of H20 and incorporated in a photographic emulsion. former was non-diffusing in the emulsion and the emulsion could be cast on a suitable support, in accordance with conventional practice, to pro duce a photographic film. After exposure and development of the film with a color forming developer, p diethylaminoaniline, a magenta picture was obtained.

Example 2 2-keto-4-chloro-imidazo [1,2-a] quinoline was prepared as outlined in Equation I above. This material was incorporated in a photographic emulsion in a conventional way, for instance, as outlined under Example 1 above, and the emulsion cast on a suitable support, in accordance with conventional practice, to produce a photographic film. After exposure and development with a color forming developer, p-diethylaxninoaniline, a magenta picture was obtained.

The thus obtained color Equation I above, substituting 2-octadecyleminoquinoline for the 2-aminoquinoline there specifled. This color former was sulfonated in order to improve its solubility and was then dissolved in en aqueous solution end added to a photographic emulsion in the manner specified in Example I above. The color former was found to be non-dimming in the photographic emulsion. The emulsion containing the color former was cast on a suitable support, in accordance with conventional practice, to produce a, photographic film. After development with a. color forming developer, p-diethylnminonniline, a, magenta pLture was obtained,

Still another method oi overcoming the t: it:

lit

culty of diffusion is to treat the 2-keto-d-chlorolmidezo [1,2-a] quinoline with n long chain ncyl chloride, for instance, with steeryl chloride which results in the introduction of e stearyl group on the nitrogen in the 1-position to give l-steoryl-ilketo-d-chloro-imndnzo [1,2-n] quinoline.

The introduction of n long chain acyl group into the i-position of the dose [1,2-a] pyridine compound does not olwnys proceed satisfactorily by the method just described, 1. e., treating the imidnzo [1,2-e] pyridine compound with on ncyl halide.

An alternative method that in most cases gives better yields and more ensily purifieble products consists in treating an inner cyclic salt, referred to above, (B) in Equation H, with a. long chain aliphatic ocid nnhydride, for exemple stearic acid enhydride. Thus, gently worming together 0 and stenric acid anhydride resulted in an almost quantitative yield of G O-CnHat N I \i O N-JJH2 C sCUHaa which was a blue magenta 'non-diflusing color by hydrogen, methyl, nitro, chloro, amino, etc.

Dyes with absorption maxima close to 580 mu. were obtained from 2-keto-4-chloro-imidazo [1,2-a] quinolines substituted in the 1-position by hydrogen, alkyl, or acyl, and in the quinoline ring by hydrogen, methyl, nitro, chloro, amino, etc.

Other specific color formers of the type embodied in the present invention are listed below in tabular form, together with the spectral abp ion maximum for the dyes produced on color forming development with p-aminodiethyianiline of exposed photographic gelatine'silver halide emulsions in which these color formers had been incorporated as outlined above.

Example 3 Spectral Color Former Absorption Maximum l-s.cetyl-2-keto-4-acetate-9-methyl-imidnzo [1,2-23] quinoline (I) 0 Q Hi HaC N\ Ha 580 MU. C 020 Ht Example 4 S ectral Color Former nb orption Maximum l-acetyl-hketo-i-acetate imidazo [1,2-a] quinoline oooni N\ v A! H: 580 Mu. H 0 020111! Example 5 I S ctral Color Former Ab i-ption Maximum 2-lreto-4-chloro-5-methyi-imidazo-[l,2-a] pyridine NEE W 00 N-'-Hr 560 Mn.

Example 6 Spectral Color Former Absorption Maximum l-propionyi-z-lteto-i-propionate-B-chloro-imidazo [1,2-a] pyridine (I) 0 01H 5 H ($30 560 Mu.

N- H: 0M0 O2C2Ht Example 7 Spectral Color Former Absorption Maximum l-acetyl-2-keto-4-acetatc-6-nitro-lmldaz0-[l,2-a] pyridine (i) OICHI or w N-fll O N COICHI Example 8 Spectral Color Former Absorption Maximum 2-keto-4-chloro-imidozo [l ,2-a] isoquinolinc N5 sso Mu.

Example 9 Spectral Color Former Absorption Maximum 2-keto-4-chioro-6-amino-iruidazo [Li-a] pyridine C 0 N 3111: HiN Cl I claim:

1. A photographic element comprising a silver halide photographic emulsion containing as a color forming development component an imidazolone of the formula idazolone of the formula wherein the pyridine ring may bear substituents selected from the group consisting of lower alkyl, nitro, halo and amino groups, and wherein X a is a negative ion of a quaternary ammonium salt, and R is a member of the group consisting of H, alkyl, aryl, aralkyl, and acyl.

3. The method of producing color pictures which comprises developing a silver halide photographic emulsion with a color forming developer in the presence of a color forming development component of the formula I o c o wherein R represents the residue of a member of the group consisting of pyridine, quinoline and isoquinoline radicals, R represents a member of the group consisting of H. alkyl, aryl, aralkyi. and acyl, and X is a negative ion or a quaternary ammonium salt. v

4. The method 'of producing color pictures which comprises developing a silver halide photographic emulsion'with a color forming developer in the presence of a color forming development component of the formula wherein the pyridine ring may bear substituents selected from the group consisting of lower alkyl, nitro, halo and amino groups, and wherein X is a negative ion of a quaternary ammonium salt, and R is a. member of the group consisting of H, alkyl, aryl, aralkyl, and'acyl.

5. A photographic element comprising a silver halide photographic emulsion containing as a color forming development component an im-.

idazolone of the formula v /\I/ N\--'JJHI x wherein the quinoline radical may bear substituents selected from the group consisting of lower alkyl, nitro, halo and amino groups, and wherein X is a negative ion of aquaternary ammonium salt, and R is a member of the group consisting of H, alkyl, aryl, aralkyl, and acyl.

7. A photographic element comprising a silver halide photographic emulsion containing as a color forniingvdevelopment component an imidazolone or the formula wherein the-ouinoline residue may bear SubStit! uents selected from the group consisting of lower alkyl, nitro, halo and amino groups, and wherein X is a negative ion of a quaternary ammonium; group consisting salt, and R'is a member of the of'H. alkyl, aryl, aralkyl, and acyl.

8. The method of producing color pictures which comprises'developing a silver halidephotographic emulsion with a color forming developer in the presence of a color forming development component of the formula V c-l=o wherein the quinoline residue may bearsubstituents selected from-the group consisting of lower alkyl, nitro, halo-and amino groups, and wherein X- is a negative ion of a quaternary ammonium salt, and R is a'member of the group-consisting of H.alkyl, aryLaraIkYI, and acyl.

9. A photographic element comprising a silver halide photographic, emulsion containing asa color forming development component an im-' iciazolone'ofv the formula wherein 'R' represents the residue of a member of the grouponsistingoi pyridine, quinoline and lsoqHinolme radicals, R is a long chain 'alkyl ammonium salt.

group, and x is a negative ion of a quaternary 10 u I a 10. The method of producing color pictur which comprises developing a silver halide photographic emulsion with a color forming developer in the presence ofa color forming development wherein R represents the residueof a member of the group consisting of pyridine, quinoline and isoquinoline radicals, R is a long chain alkyl group; and X is a negative ion of a quaternary ammonium salt.

11. The method of producing color pictures which comprises developing a photographic silver halide emulsion with aprimary aromatic amino developer in the presence of a color coupler having' the formula =0 k/lL l- Hr wherein X is a negative ion.

BENJAMIN RAMAGE HARRIMAN.

REFERENCES crrnn The following references are of record in the file of this patent:

UNITED STATES PATENTS Great Britain Apr. 3, 1940 

